Institute for Food Quality and Food Safety, University of Veterinary Medicine Hannover, Foundation, Hannover, Germany.
German Federal Institute for Risk Assessment (BfR), Berlin, Germany.
PLoS One. 2020 Sep 17;15(9):e0239312. doi: 10.1371/journal.pone.0239312. eCollection 2020.
Contaminated poultry meat is considered to be the main source of human infection with Campylobacter spp., a pathogen that asymptomatically colonizes broiler chickens during fattening and contaminates carcasses during slaughter. To prevent or reduce the colonization of broiler flocks with Campylobacter spp., applying different organic acids, especially in combinations, via feed or drinking water seems to be a promising approach. However, only very few combinations of organic acids have been tested for their antibacterial efficacy against Campylobacter spp. Therefore, the in vitro susceptibility of 30 Campylobacter spp. isolates (20 C. jejuni and ten C. coli) to ten organic acids and ten combinations was determined. The testing of minimum inhibitory concentration (MIC) values was performed at pH 6.0 and 7.3 by using the broth microdilution method and included the following organic acids: Caprylic acid, sorbic acid, caproic acid, benzoic acid, ascorbic acid, propionic acid, acetic acid, formic acid, fumaric acid and tartaric acid and combinations thereof. The lowest MIC values were seen for caprylic acid (MIC range at pH 7.3: 0.5-2 mmol/L) and sorbic acid (MIC range at pH 7.3: 1-4 mmol/L). One to two dilution steps lower MIC values were determined at the lower pH value of 6.0. Furthermore, ten combinations consisting of three to five organic acids were developed. In addition to the tested antibacterial activity, other criteria were included such as approval as feed additives, reported synergistic effects and chemical properties. For nine of ten combinations, the MIC90 values of the organic acids decreased 1.25- to 241.5-fold compared to the MIC90 values for the individual substances. Furthermore, nine of ten combinations exhibited synergistic activities against two or more of the tested C. jejuni and C. coli isolates. A combination of caprylic acid, sorbic acid and caproic acid exhibited synergistic activities against the largest number of Campylobacter spp. isolates (six C. jejuni and four C. coli) with fractional inhibitory concentration (FIC) indices (∑FIC) ranging from 0.33 to 1.42. This study shows in vitro synergistic activities of different organic acids in combinations against the major Campylobacter species and could therefore be a promising basis for reducing Campylobacter spp. in vivo.
受污染的禽肉被认为是人类感染弯曲菌属的主要来源，该病原体在肉鸡育肥期间无症状定植，并在屠宰过程中污染胴体。为了预防或减少肉鸡群体中弯曲菌属的定植，通过饲料或饮用水添加不同的有机酸，特别是组合使用，似乎是一种很有前途的方法。然而，只有极少数的有机酸组合被测试过对弯曲菌属的抗菌功效。因此，本研究测定了 30 株弯曲菌属（20 株空肠弯曲菌和 10 株大肠弯曲菌）对 10 种有机酸及其组合的体外敏感性。最低抑菌浓度（MIC）值的检测在 pH6.0 和 7.3 下通过肉汤微量稀释法进行，包括以下有机酸：辛酸、山梨酸、己酸、苯甲酸、抗坏血酸、丙酸、乙酸、甲酸、富马酸和酒石酸及其组合。辛酸（pH7.3 时 MIC 范围：0.5-2mmol/L）和山梨酸（pH7.3 时 MIC 范围：1-4mmol/L）的 MIC 值最低。在 pH 值较低的 6.0 下，MIC 值低一个或两个稀释度。此外，开发了十种由三种至五种有机酸组成的组合。除了测试的抗菌活性外，还包括作为饲料添加剂的批准、报告的协同作用和化学性质等其他标准。十种组合中的九种的 MIC90 值与单一物质相比降低了 1.25-241.5 倍。此外，十种组合中的九种对两种或更多测试的空肠弯曲菌和大肠弯曲菌分离株表现出协同作用。辛酸、山梨酸和己酸的组合对最大数量的弯曲菌属分离株（六株空肠弯曲菌和四株大肠弯曲菌）表现出协同作用，其部分抑菌浓度（FIC）指数（∑FIC）范围为 0.33-1.42。本研究显示了不同有机酸组合在体外对主要弯曲菌属的协同作用，因此可能是减少体内弯曲菌属的有前途的基础。
